How do you ensure that all old brake fluid is gone?

[aoysgelt]

Planning on replacing brake fluid with high performance version but - unless I use blue one - how can I tell when old fluid has been replaced?

Current thought is to
- remove old liquid from reservoir
- estimate amount of liquid in master cylinder + each brake lines/caliper
- then flush each corner keeping track of how much fluid has been added to the system. For first corner there should be at least that corner's amount plus master cylinder/etc. each other corner should just be that corner's amount.

Any other advice?

Thanks

[Amirsm3]

You can tell the difference between used brake fluid and new brake fluid - regardless of the color you're using.

[Harry Da Hamster]

You need to go to a BMW shop to replace ALL old brake fluid. The traditional pump and release method will not flush old brake fluid in the ABS module.

[Amirsm3]

Originally Posted by FNG

You need to go to a BMW shop to replace ALL old brake fluid. The traditional pump and release method will not flush old brake fluid in the ABS module.

ohhhhh I learned something new lol

[nickdrivesm3]

You need a pressure bleeder connected to the brake fluid reservoir

[Harry Da Hamster]

That still won't remove old brake fluid from the ABS module.

Maybe the best solution (haven't tried it though) would be to flush using the traditional method or with a Motive Pressure Bleeder then do several panic stops on wet road to get the ABS to engage. After several stops, bleed the brake system again.